1. Field of the Invention
The present invention relates to a vision processing method and device for automatically tracking welding lines in an arc welding process, and more particularly, to a welding line vision processing method and device for obtaining information about a position and shape of a welding line, which is transmitted to a control unit of a welding torch, so that the welding torch can automatically track the welding line in an arc welding process through a robot.
2. Description of the Related Art
Generally, an automatic arc welding process requires a user to photograph a shape of a welding line by utilizing a laser beam, and to process data about its shape through a computer to gather the information about the position and shape of the welding line, thereby providing for a control of movement of a welding torch by utilizing the position and shape information.
A conventional technique processing the shape of the welding line, as shown in FIGS. 1A through 1C, includes three steps being performed in consecutive order. That is to say, FIG. 1A shows data obtained by observing, with a CCD (camcorder) camera, bands of the laser beams projected onto a front part of the torch, FIG. 1B shows central coordinates of the laser bands obtained by a result of FIG. 1A, and FIG. 1C shows intersecting points between the lines formed by the central coordinates. Positions of joining parts of an object are determined through information obtained from the intersecting points as shown in FIG. 1C.
The image of the laser band, as shown in FIG. 1A, is obtained by photographing with a camcorder the laser band projected on the front part of the torch during the welding process. The central coordinates of the laser bands in FIG. 1B include points indicating the maximum output on the image of the laser bands. The points are obtained by a laser band detecting filter which has a weighted value of a distribution shown in FIG. 2. That is, the two-dimensional image data, as shown in FIG. 1A, is changed to data such as that in FIG. 1B by the laser band detecting filter.
At this time, the weighted value of the laser band detecting filter should be designed to be zero in its total, and the filter effectively responds in its function when a clear band having an even thickness is formed horizontally on its image. The position of the welding joint and its shape are determined in response to the result obtained by fitting a plurality of lines, as shown in FIG. 1C, thereby controlling the welding torch to process the arc welding on the basis of such data.
However, there is a problem in the conventional method thus performed in that it is difficult to utilize this method in an arc welding process in which a high voltage is needed, as the results are badly affected by welding noises such as an arc light or spattering caused by the welding.